Preparation method of 5N-grade high-purity rhenium powder

Abstract

The invention belongs to the technical field of scattered metal, and particularly relates to a preparation method of 5N-grade high-purity rhenium powder. In the prior art, industrial-grade ammonium perrhenate is generally used as a raw material, and 5N-grade high-purity ammonium perrhenate is obtained through ion exchange resin adsorption separation. And the 5N-grade high-purity ammonium perrhenate is subjected to hydrogen reduction to prepare the 5N-grade high-purity rhenium powder. The preparation method has the problems of complex purification process, low purification efficiency and low purification rate. The invention discloses a preparation method of 5N-grade high-purity rhenium powder, which is characterized in that industrial ammonium perrhenate with the content of 99.9% is subjected to precision filtration and two times of recrystallization to prepare 5N-grade high-purity ammonium perrhenate. And reducing the 5N-grade high-purity ammonium perrhenate with hydrogen to prepare the 5N-grade high-purity rhenium powder. The preparation method of the 5N-grade high-purity rhenium powder has the advantages of being simple in preparation process, high in purification efficiency and high in purification rate.

Description

Technical Field

[0001] The present application belongs to the field of scattered metal technology, and specifically relates to a method for preparing 5N grade high-purity rhenium powder. Background Art

[0002] Metal rhenium (Re), atomic number: 75, density: 21.04 g / cm 3 , melting point: 3186℃, boiling point: 5596℃. Rhenium metal is one of the rarest metals on earth, with an average estimated content of one part per billion. It is a by-product of the molybdenum and copper refining process. Rhenium powder is a gray metal powder, mainly used as the base material for various rhenium components and as a rhenium element additive for various high-temperature alloys. The main methods for preparing rhenium powder are: hydrogen reduction method, electrolysis method, and halide thermal dissociation method. The content of rhenium powder obtained by the above three preparation methods is completely dependent on the quality of the raw materials. The rhenium powder obtained usually has a content of 99.99%, which cannot be used in high-end fields.

[0003] CN 113857488A (2021) discloses a method for producing high-purity, ultrafine rhenium powder using ammonium perrhenate. This method uses 99% industrial crude ammonium perrhenate as the raw material. First, oxygen-enriched air is introduced into a rotary roaster at high temperature to produce rhenium oxide powder. The rhenium oxide powder is then heated in a staged hydrogen reduction furnace to generate rhenium oxide vapor. Finally, a multi-stage, high-temperature reduction reaction with hydrogen is carried out to produce high-purity, ultrafine rhenium powder. This method, which produces 99.99% rhenium powder using 99% industrial crude ammonium perrhenate as the raw material, suffers from a low rhenium content.

[0004] CN 115072789A (2022) discloses a method for preparing high-purity ammonium rhenate. This method involves washing an anion exchange resin adsorbed with rhenate with water to remove potassium ions. The washed anion exchange resin is then desorbed with ammonia to produce a rhenium-rich solution. Ammonium rhenate is then recovered from the rhenium-rich solution. This method suffers from a complex process and low product content.

[0005] In summary, the existing methods for further preparing high-purity rhenium powder by purifying ammonium perrhenate generally have the problems of complex purification process, low purification efficiency, low purification rate and low product content. Summary of the Invention

[0006] In response to the above technical problems, the present application aims to provide a method for preparing 5N grade high-purity rhenium powder, which is carried out according to the following steps:

[0007] S1, dissolving crude ammonium perrhenate in hot water to generate a first solution;

[0008] S2, the first dissolved liquid is finely filtered to generate a filtrate;

[0009] S3, the filtrate is cooled, crystallized, and filtered under the shearing action of a high-speed shear device to generate micron crystals;

[0010] S4, the micron crystals are dissolved in hot water to generate a second solution;

[0011] S5, the second solution is cooled, crystallized, and filtered under the shearing action of a low-speed shear device to generate millimeter crystals;

[0012] S6, millimeter crystals are reduced with hydrogen to produce 5N grade high purity rhenium powder;

[0013] The content of the crude ammonium perrhenate in step S2 is ≥99.9%.

[0014] It can be seen that the present application prepares 5N grade high-purity rhenium powder from crude ammonium perrhenate through precision filtration, two recrystallizations, and hydrogen reduction processes. The content of crude ammonium perrhenate is ≥99.9%. Commercially available industrial ammonium perrhenate can be purified to above 99.9% by other methods and then purified by the method described in the present application. In order to purify the content of ammonium perrhenate to above 99.999%, the present application first dissolves the crude ammonium perrhenate in hot water to generate a first dissolving solution. The first dissolving solution is precision filtered to generate a filtrate. The hot water here must be deionized water or distilled water. The first dissolving solution is precision filtered to remove trace insoluble matter therein. These insoluble matter are mainly metal ion salts or other impurities with relatively low solubility in water; then, the filtrate is cooled, crystallized, and filtered under the action of a high-speed shearing device to generate micron crystals. The process for producing micron crystals involves rapid cooling and sufficient turbulence to induce the precipitation of ammonium perrhenate from water into micron-sized crystals, maximizing the complete precipitation of the ammonium perrhenate from the filtrate as micron-sized crystals. Due to the rapid turbulent crystallization, the rate of nucleation is much greater than the rate of nucleus growth, trapping the mother liquor within the interstices of the crystals. However, the nucleus concentration is extremely high. The mother liquor is enriched with a small amount of impurity ions that have not yet integrated into the crystal lattice. Next, the micron-sized ammonium perrhenate is dissolved in hot water to produce a second solution. This second solution is cooled, crystallized, and filtered under the influence of a low-speed shear device to produce millimeter-sized crystals. The process for producing millimeter-sized crystals involves slow cooling and low-speed laminar flow to induce the precipitation of ammonium perrhenate from water into millimeter-sized crystals, maximizing the complete precipitation of the ammonium perrhenate from the second solution as millimeter-sized crystals. Since impurity ions that can be embedded in the crystal lattice are removed during the process of generating micron crystals, the crystals obtained in this crystallization process contain very little mother liquor, and there are no impurity ions that can be embedded in the crystal lattice, resulting in high-content ammonium perrhenate crystals, which improves the quality of ammonium perrhenate. Simply put: The separation principles of this application are: 1. Separate impurity ions that are difficult to dissolve or insoluble in water through precise filtration; 2. Separate impurity ions that are easily embedded in the crystal lattice through rapid crystallization; 3. Separate impurity ions that are easily wrapped in the crystals through slow crystallization. Finally, the ammonium perrhenate millimeter crystals are reduced with hydrogen to produce 5N grade high-purity rhenium powder.

[0015] The above is the basic technical solution of this application. To facilitate those skilled in the art to understand and implement the technical solution of this application, this application also includes the following additional technical features:

[0016] In a preferred technical solution, the mass ratio of the hot water to the crude ammonium perrhenate in step S1 is 6-12:1, and the hot water temperature is 70-90°C. The hot water quality and temperature required to completely dissolve the crude ammonium perrhenate are sufficient. When a large amount of hot water is used, a lower temperature can be used; when a small amount is used, a higher temperature can be used. During the dissolution of the crude ammonium perrhenate, continuous stirring can be used to increase the dissolution rate. The hot water completely dissolves the crude ammonium perrhenate, generating a first solution.

[0017] In the preferred technical solution, the precision filtration process described in step S2 is carried out in a precision filter with a filter mesh pore size of 20-50 μm. There are more or less trace amounts of insoluble matter in the first dissolution, and the insoluble matter in the first dissolution can be separated by a precision filter. If the insoluble matter in the first dissolution is not separated, it will serve as a crystal nucleus to promote the subsequent cooling crystallization process, and will be brought into the micron crystallization, reducing the quality of ammonium perrhenate. The present application carries out the precision filtration process described in step S1 in a precision filter with a filter mesh pore size of 20-50 μm, which can separate trace amounts of complex salts, colloidal particles or other impurities.

[0018] In a preferred technical solution, the high-speed shearing device in step S3 is selected from a stator-rotor shearing mechanism and a dispersion disk. Under the shearing action of the high-speed shearing device, such as the stator-rotor shearing mechanism or the dispersion disk, the filtrate is subjected to intense turbulence. This, coupled with rapid cooling, allows the ammonium perrhenate in the first solution to rapidly precipitate as micron-sized crystals, precipitating as much ammonium perrhenate as possible in the form of micron-sized crystals. Impurity ions that are easily embedded in the crystal lattice are retained in the mother liquor.

[0019] In the preferred technical solution, during the cooling crystallization process described in step S3, the impeller linear velocity of the high-speed shearing device is controlled to be 15-25 m / s. In order to precipitate micron-level ammonium perrhenate crystals in the system, it is necessary to control the flow state of the system to be in a sufficiently turbulent state. At this time, the requirement can be met by controlling the impeller linear velocity of the high-speed shearing device to be 15-25 m / s. When the impeller linear velocity of the high-speed shearing device is lower than 15 m / s, the particle size of the ammonium perrhenate crystals is too large, the precipitation crystallization speed is too slow, and impurity ions are easily embedded in the crystal lattice. When the impeller linear velocity is greater than 25 m / s, the particle size of the ammonium perrhenate crystals is too small, the filtration process is too slow, and it is not conducive to normal operation.

[0020] In the preferred technical solution, in the cooling crystallization process described in step S3, the cooling rate of the cooling crystallization process is controlled to be 1.0-5.0℃ / min; and the final temperature of the cooling crystallization process is controlled to be 5-10℃. In the cooling crystallization process described in step S3, the faster the cooling rate, the faster the crystallization rate, and the smaller the crystal particle size; the slower the cooling rate, the slower the crystallization rate, and the larger the crystal particle size. In order to obtain micron crystals during the first cooling crystallization, the present application needs to adopt the fastest possible cooling rate, and a cooling rate of 1.0-5.0℃ / min is adopted at this time. The cooling rate cannot be too fast. On the one hand, the cooling rate is limited by the heat transfer capacity of the equipment. On the other hand, if the cooling rate is too fast, the crystal particle size precipitated will be too small, and the filtration rate will be slow.

[0021] In a preferred technical solution, the mass ratio of the hot water to the micron-crystals in step S4 is 5-10:1; the temperature of the hot water is 70-90°C. The mass and temperature of the hot water for dissolving the micron-crystals are required to completely dissolve the ammonium perrhenate micron-crystals. When a large amount of hot water is used, a relatively low hot water temperature can be used; when a small amount of hot water is used, a relatively high hot water temperature can be used. During the dissolution of the ammonium perrhenate micron-crystals, the dissolution rate can be increased by continuous stirring. The hot water completely dissolves the ammonium perrhenate micron-crystals to generate a second solution. The amount of water used to dissolve the micron-crystals is less than the amount of water used to dissolve the crude ammonium perrhenate. This is because the number of micron-crystals is calculated based on the wet micron-crystals, and the micron-crystals contain a certain amount of water.

[0022] In a preferred technical solution, the low-speed shear device in step S5 is selected from a flat-blade paddle stirrer, an anchor stirrer, or a frame stirrer. Under the stirring action of the low-speed shear device, such as a flat-blade paddle stirrer, an anchor stirrer, or a frame stirrer, the second solution is in a stable laminar flow state, supplemented by slow cooling, so that pure large-particle ammonium perrhenate crystals are precipitated from the second solution, and as much ammonium perrhenate as possible is precipitated in the form of millimeter crystals, without impurity ions embedded in the crystal lattice and without encapsulating the mother liquor in the crystals. Impurity ions are enriched in the crystallization mother liquor, resulting in 5N grade high-purity ammonium perrhenate crystals.

[0023] In the preferred technical solution, during the cooling crystallization process described in step S5, the impeller linear velocity of the low-speed shearing device is controlled to be 0.05-0.5 m / s. In order to precipitate millimeter-level ammonium perrhenate crystals in the system, the flow state of the system needs to be controlled to be laminar flow. At this time, the requirement can be met by controlling the impeller linear velocity of the low-speed shearing device to be 0.05-0.5 m / s. When the impeller linear velocity is lower than 0.05 m / s, the particle size of the ammonium perrhenate crystals is large, but the heat transfer rate is slow, the cooling rate is slow, and the time for crystallization is long. When the impeller linear velocity is greater than 0.5 m / s, the particle size of the ammonium perrhenate crystals is small, and the specific surface area of ​​the crystals is large, which will adsorb other impurity ions in the crystallization mother liquor and reduce the quality of the ammonium perrhenate crystals.

[0024] In the preferred technical solution, the cooling rate of the cooling crystallization process is controlled to be 0.1-0.5°C / min during the cooling crystallization process in step S5; and the final temperature of the cooling crystallization process is controlled to be 5-10°C. In the cooling crystallization process in step S5, the faster the cooling rate, the faster the crystallization rate, and the smaller the crystal particle size; the slower the cooling rate, the slower the crystallization rate, and the larger the crystal particle size. In order to obtain millimeter crystals during the second cooling crystallization, the present application needs to adopt the slowest possible cooling rate, and a cooling rate of 0.1-0.5°C / min is adopted at this time. The cooling rate cannot be too slow, otherwise the cooling crystallization time will be extremely long, and the efficiency of the purification process will be low.

[0025] In summary, first, slightly soluble or poorly soluble impurities in the crude ammonium perrhenate product are separated through precision filtration; then, impurity ions that are easily embedded in the ammonium perrhenate crystal lattice are separated through rapid crystallization; then, impurity ions that are easily encapsulated in the ammonium perrhenate crystals are separated through slow crystallization; finally, 5N grade high-purity rhenium powder is prepared through hydrogen reduction. The method for preparing 5N grade high-purity rhenium powder described in this application has the characteristics of a simple purification process, high purification efficiency, high purification rate, and high product content. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0027] Example 1

[0028] (1) Preparation of the first dissolving solution:

[0029] Add 50.000g of crude ammonium perrhenate (99.9312%) and 400g of 85°C deionized water to an 800ml beaker. Stir and dissolve while maintaining the temperature. Once dissolved, you will obtain the first solution.

[0030] (2) Precision filtration:

[0031] The first dissolved solution was filtered on a G3 sand core funnel while hot to obtain a filtrate.

[0032] (3) Preparation of micronized ammonium perrhenate crystals:

[0033] Transfer the filtrate to a clean 800ml beaker and place it in a water bath. Submerge the shearing head of the stator-rotor shear mechanism (rotor diameter: 3.5cm) below the surface of the filtrate. Start the stator-rotor shear mechanism and set the speed to 11,000 rpm and the rotor linear speed to approximately 20.1 m / s. Add a mixture of ice and brine to the water bath to rapidly cool the filtrate to 5°C over approximately 30 minutes. After crystallization is complete, filter to yield 70.159g of micronized ammonium perrhenate crystals with a water content of 32.5%. Collect the filtrate for centralized processing.

[0034] (4) Preparation of the second dissolving solution:

[0035] Transfer the micronized ammonium perrhenate crystals to a clean 800ml beaker, add 500g of 85°C deionized water to the beaker, and dissolve while stirring. Once dissolved, a second solution is obtained.

[0036] (5) Preparation of mm ammonium perrhenate crystals:

[0037] Place the beaker in an 85°C waterbath and submerge a mechanical stirring paddle (5.0 cm diameter) below the surface of the second solution. Start mechanical stirring at 60 rpm and a paddle speed of 0.157 m / s. Slowly lower the water bath temperature and allow the crystals to cool. After approximately 3.5 hours, lower the beaker temperature to 5°C. After crystallization is complete, filter and dry to yield 45.124 g of ammonium perrhenate crystals with an ammonium perrhenate content of 99.9995%.

[0038] (6) Reduction:

[0039] The millimeter ammonium perrhenate crystals were transferred to a quartz boat, which was then placed in a tube furnace. Hydrogen was introduced into the furnace at 750°C for 5 hours to reduce the material. This yielded 31.325 g of high-purity rhenium powder, containing 99.9995 wt% rhenium, with a metallic rhenium recovery rate of 90.31%.

[0040] Example 2

[0041] The preparation process and process parameters of Example 2 were essentially the same as those of Example 1, with the exception that the stator and rotor speeds were set at 13,600 rpm and a rotor linear speed of approximately 24.9 m / s during the preparation of micronized ammonium perrhenate crystals. 46.456 g of millimeter-sized ammonium perrhenate crystals were obtained, with a rhenium content of 99.9990%. Finally, 32.249 g of high-purity rhenium powder was obtained, with a rhenium content of 99.9990%, and a rhenium metal recovery rate of 92.98%.

[0042] Example 3

[0043] The preparation process and process parameters of Example 3 were essentially the same as those of Example 1, with the exception that the stator and rotor speeds were set at 8200 r / min and the rotor linear speed was approximately 15.0 m / s during the preparation of micronized ammonium perrhenate crystals. 44.571 g of millimeter ammonium perrhenate crystals were obtained, with a rhenium content of 99.9993%. Finally, 30.941 g of high-purity rhenium powder was obtained, with a rhenium content of 99.9993%, and a metallic rhenium recovery rate of 89.20%.

[0044] Example 4

[0045] The preparation process and process parameters of Example 4 were essentially the same as those of Example 1, except that the temperature of the filtrate in the beaker was lowered to 5°C for approximately 16 minutes during the preparation of micron-sized ammonium perrhenate crystals. 45.787 g of millimeter-sized ammonium perrhenate crystals with a rhenium content of 99.9990% were obtained. Finally, 31.785 g of high-purity rhenium powder with a rhenium content of 99.9990% was obtained, resulting in a rhenium metal recovery rate of 91.64%.

[0046] Example 5

[0047] The preparation process and process parameters of Example 5 were essentially the same as those of Example 1, except that the temperature of the filtrate in the beaker was lowered to 5°C for approximately 80 minutes during the preparation of micronized ammonium perrhenate crystals. 44.771 g of millimeter ammonium perrhenate crystals with a rhenium content of 99.9995% were obtained. Finally, 31.080 g of high-purity rhenium powder with a rhenium content of 99.9995% was obtained, resulting in a metallic rhenium recovery rate of 89.60%.

[0048] Example 6

[0049] The preparation process and process parameters of Example 6 were essentially the same as those of Example 1, with the exception that the mechanical stirring speed was set at 190 r / min and the flat-blade slurry linear velocity was approximately 0.5 m / s during the preparation of the millimeter ammonium perrhenate crystals. 46.241 g of millimeter ammonium perrhenate crystals were obtained, with a rhenium content of 99.9992%. Finally, 32.100 g of high-purity rhenium powder was obtained, with a rhenium content of 99.9992%, and a rhenium metal recovery rate of 92.54%.

[0050] Example 7

[0051] The preparation process and process parameters of Example 7 were essentially the same as those of Example 1, with the exception that the mechanical stirring speed was set at 20 r / min and the flat-blade slurry linear velocity was approximately 0.05 m / s during the preparation of the millimeter ammonium perrhenate crystals. 45.541 g of millimeter ammonium perrhenate crystals were obtained, with a rhenium content of 99.9997%. Finally, 31.614 g of high-purity rhenium powder was obtained, with a rhenium content of 99.9997%, and a rhenium metal recovery rate of 91.14%.

[0052] Example 8

[0053] The preparation process and process parameters of Example 8 were essentially the same as those of Example 1, except that the temperature of the second dissolving solution in the beaker was lowered to 5°C for approximately 160 minutes during the preparation of millimeter ammonium perrhenate crystals. 46.217 g of millimeter ammonium perrhenate crystals with a rhenium content of 99.9990% were obtained. Finally, 32.083 g of high-purity rhenium powder with a rhenium content of 99.9990% was obtained, resulting in a rhenium metal recovery rate of 92.50%.

[0054] Example 9

[0055] The preparation process and process parameters of Example 9 were essentially the same as those of Example 1, except that the temperature of the second dissolving solution in the beaker was lowered to 5°C for approximately 780 minutes during the preparation of millimeter-perrhenate crystals. 46.652 g of millimeter-perrhenate crystals with a rhenium content of 99.9997% were obtained. Finally, 32.385 g of high-purity rhenium powder with a rhenium content of 99.9997% was obtained, resulting in a rhenium metal recovery rate of 93.37%.

[0056] Comparative Example 1

[0057] The preparation method and process parameters of Comparative Example 1 were essentially the same as those of Example 1, except that the first solution was directly used in the subsequent steps without precision filtration. 46.253 g of ammonium perrhenate crystals were obtained, with a rhenium content of 99.9984%. Finally, 32.108 g of high-purity rhenium powder was obtained, with a rhenium content of 99.9984%, and a rhenium recovery rate of 92.57%.

[0058] Comparative Example 2

[0059] The preparation process and process parameters of Comparative Example 2 were essentially the same as those of Example 1, except that the temperature of the second dissolving solution in the beaker was lowered to 5°C for approximately 60 minutes during the preparation of millimeter ammonium perrhenate crystals. 46.211 g of millimeter ammonium perrhenate crystals with a rhenium content of 99.9976% were obtained. Finally, 32.079 g of high-purity rhenium powder with a rhenium content of 99.9976% was obtained, resulting in a rhenium metal recovery rate of 92.48%.

[0060] Comparative Example 3

[0061] The preparation process and process parameters of Comparative Example 3 were essentially the same as those of Example 1, except that the mechanical stirring speed was set at 300 r / min and the flat-blade slurry linear velocity was approximately 0.79 m / s during the preparation of the millimeter ammonium perrhenate crystals. 45.954 g of millimeter ammonium perrhenate crystals were obtained, with a rhenium content of 99.9973%. Finally, 31.901 g of high-purity rhenium powder was obtained, with a rhenium content of 99.9973%, and a rhenium metal recovery rate of 91.97%.

[0062] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing 5N grade high-purity rhenium powder, characterized in that: The preparation method is carried out according to the following steps: S1, dissolving crude ammonium perrhenate in hot water to generate a first solution; S2, the first dissolved liquid is finely filtered to generate a filtrate; S3, the filtrate is cooled, crystallized, and filtered under the shearing action of a high-speed shear device to generate micron crystals; S4, the micron crystals are dissolved in hot water to generate a second solution; S5, the second solution is cooled, crystallized, and filtered under the shearing action of a low-speed shear device to generate millimeter crystals; S6, millimeter crystals are reduced with hydrogen to produce 5N grade high purity rhenium powder; The content of the crude ammonium perrhenate in step S2 is ≥99.9%.

2. The preparation method according to claim 1, characterized in that In step S1, the mass ratio of the hot water to the crude ammonium perrhenate is 6-12:1; and the temperature of the hot water is 70-90°C.

3. The preparation method according to claim 1, characterized in that The precision filtration process described in step S2 is performed in a precision filter with a pore size of 20-50 μm.

4. The preparation method according to claim 1, characterized in that The high-speed shearing device in step S3 is selected from a stator-rotor shearing mechanism and a dispersion disk.

5. The preparation method according to claim 1, characterized in that During the cooling crystallization process in step S3, the impeller linear speed of the high-speed shearing device is controlled to be 15-25 m / s.

6. The preparation method according to claim 1, characterized in that In the cooling crystallization process of step S3, the cooling rate of the cooling crystallization process is controlled to be 1.0-5.0°C / min; and the final temperature of the cooling crystallization process is controlled to be 5-10°C.

7. The preparation method according to claim 1, characterized in that In step S4, the mass ratio of the hot water to the micron crystals is 5-10:1; and the temperature of the hot water is 70-90°C.

8. The preparation method according to claim 1, characterized in that The low-speed shearing device in step S5 is selected from one of flat-blade paddle stirring, anchor stirring, and frame stirring.

9. The preparation method according to claim 1, characterized in that During the cooling crystallization process in step S5, the linear speed of the impeller of the low-speed shearing device is controlled to be 0.05-0.5 m / s.

10. The preparation method according to claim 1, characterized in that In the cooling crystallization process of step S5, the cooling rate of the cooling crystallization process is controlled to be 0.1-0.5°C / min; and the final temperature of the cooling crystallization process is controlled to be 5-10°C.